Or you could get 50mph+ out of the GG, by going to shouts with the water tank empty, as 3 Para did in Essex. The thing won't work properly until connected to a hydrant, in any case.
I was as happy doing my bit towards defeating the firefighters as I was towards defeating Saddam. I ended up on Op Telic and Op Fresco at the same time, which could have been tricky, had the fireshirkers called a strike during the war.
Anyway, enjoy. It's good fun, especially if you end up as crew, in a busy area.